Index: llvm/runtimes/CMakeLists.txt
===================================================================
--- llvm/runtimes/CMakeLists.txt
+++ llvm/runtimes/CMakeLists.txt
@@ -61,6 +61,14 @@
 
   find_package(LLVM PATHS "${LLVM_BINARY_DIR}" NO_DEFAULT_PATH NO_CMAKE_FIND_ROOT_PATH)
 
+  # find_package may have overridden some cache variables which ought not be
+  # overridden for a build using the just-built toolchain. Revert them.
+  get_cmake_property(_variableNames CACHE_VARIABLES)
+  foreach (_variableName ${_variableNames})
+      get_property(original_value CACHE ${_variableName} PROPERTY VALUE)
+      set(${_variableName} ${original_value})
+  endforeach()
+
   # Add the root project's CMake modules, and the LLVM build's modules to the
   # CMake module path.
   list(INSERT CMAKE_MODULE_PATH 0